Business reporter in New York.
For the first time in its history, Amazon will have to recognize a trade union in the US.
Workers at a warehouse in New York voted to join the Amazon Labor Union.
Chris Smalls, a former Amazon worker, is the leader of the group.
The victory of Mr Smalls marks a major defeat for Amazon.
In Alabama, where Amazon was facing a separate union drive, the company appeared to have fended off activists in a tight contest in which challenged ballots could yet overturn the result.
The two elections mark a milestone for activists who have long decried labour practices at Amazon.
Mr Smalls celebrated the win with a twist on the company's motto, "ALU for the win."
Rebecca Givan, professor of labour studies at Rutgers University, said that the defeat of Amazon by Mr Smalls and his team was a really big deal.
She warned that he will be facing a tough fight when it comes to contract negotiations.
She said that Amazon will do everything it can to stop the victory and break up the workers.
Amazon poured resources into fighting the unionising efforts, which it sees as an obstacle to business flexibility and warehouse efficiency.
The company believes it is better to work directly with workers and offers competitive pay and benefits. Representatives questioned the ability of union leaders to win more in contract negotiations after the vote.
The company didn't reply to the request for comment.
The company made critical mistakes before the vote, such as pushing to reverse policies that were relaxed under Covid.
Even though they had made a lot of effort to reach out to workers and make their case ahead of the vote, they were surprised by their win.
Karen Ponce is an Amazon worker and secretary of the Amazon Labor Union.
Mr Smalls was fired by Amazon in 2020 after he protested against the company's handling of the coronaviruses.
He established the Amazon Labor Union last year, calling for higher pay, stronger medical benefits, anti- discrimination policies and better leave.
The victory gives his group the right to negotiate a contract with Amazon for the roughly 8,000 workers at the Staten Island warehouse.
A second union campaign in the same industrial park is scheduled for a vote later this month.
There is an upswell of labour activism in the US.
Organisers have led successful campaigns at Starbucks and others.
Workers were worried about their safety. The tight labour market has been caused by the rapid rebound of the economy.
In the US, only 6.1% of private sector workers belong to unions.
Prof Givan said it was difficult for workers to organize.
Workers at the warehouse in Alabama voted against joining the Retail, Wholesale and Department Store Union.
There are more than 400 challenged ballots that could change the result.
The unofficial tally showed a much closer election than the one Amazon claimed after last year's election, which regulators later declared invalid, ordering a do-over citing labour rule violations by Amazon.
Less than 40% of the workers at the warehouse cast their votes in the election.
Stuart Appelbaum, president of the Retail Wholesale and Department Store Union, which led the unionising drive in Alabama, said he was excited by the possibility of a union victory in New York.
He said the win reflected differences between New York and Alabama, both of which are anti-labour.
He said that the initial union effort at the Amazon warehouse in Alabama had sparked a movement.
He said at a press conference on Thursday that workers here have shown what is possible despite the final outcome.